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In pictures: Giant millipedes face alien plant threat

Scientists have been studying the challenges facing Seychelles giant millipedes, currently listed as "Vulnerable" by the International Union for the Conservation of Nature. PhD student James Lawrence published his findings on the millipedes' island habitat in the Journal of Insect Behaviour.

Mr Lawrence studied the millipedes living on Cousine Island in the Indian Ocean. Although they were once abundant across the Seychelles, populations of the millipedes have been decimated on the main islands of Mahe and Praslin, due to invasive mammals.

But non-native animals are not the only concern for those working to conserve the Seychelles giant millipedes. Previous research has shown that less than 5% of the "original" vegetation remains on the islands of the Seychelles following human settlement.

Mr Lawrence assessed the effect that coconuts and bamboo, both alien plant species introduced to Cousine, had on the millipedes. He found that the plants altered the millipedes' foraging behaviour and that populations were less dense in areas where bamboo was present.

The ratio of millipedes in bamboo sites compared to natural forest was 1:11. It is suggested this is due to their feeding preference for native leaf litter. Previous studies have shown that native plants, such as figs and Pisonia grandis, have more moisture content than introduced plant species.

As part of the island's restoration project bamboo was removed and native saplings were planted in the cleared area. Although millipedes were not recorded in the cleared area during his study, Mr Lawrence predicted that, once the canopy cover is restored, the millipedes will return.

The entomologist told BBC Nature that his results have substantial impacts for the conservation of the Seychelles giant millipede, which he says is essential to the island ecosystem. "It plays a significant role in leaf-litter breakdown and nutrient dynamics," Mr Lawrence commented.

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